Tuberculosis

From ArticleWorld

Tuberculosis usually affects the lungs (a condition known as pulmonary tuberculosis) but it can also affect the central nervous system, circulatory system, lymphatic system, bones and joints.

It is the most common infectious disease today, affecting about one third of the world's population. However, the vast majority of those infected have asymptomatic, latent TB. Few of these people actually develop the active form, which kills about 50% of those infected. A TB control program was started in the 1980s, but neglected with the expansion of the HIV/AIDS. This lead to a major resurgence of tuberculosis, leading WHO to declare it a global health emergency in 1993.

Symptoms and diagnosis

TB is spread by inhalation of airborne droplets expelled by people suffering from the active form of the disease. Close contact has also been reported as a way of transmission. When the Mycobacterium tuberculosis bacilli reach the pulmonary alveoli, they infect alveolar macrophages and begin to multiply. They can spread, helped by the dendritic cells, to other organs as well, including the kidneys and the brain.

TB causes symptoms including prolonged and productive cough that lasts for several weeks, fever, appetite and weight loss and exhaustion. The complete diagnosis procedure involves an examination of the medical history, a physical examination including a tuberculin skin test, X-ray, microbiological cultures and a serological test.

Treatment and prevention

The treatment depends on the form of tuberculosis displayed by the patient. It involves a combination of rifampicin, isoniazid, pyrazinamide and ethambutol in the first phase, reduced later if the bacteria are resistant to any of them. A careful monitoring of the treatment is required. A vaccine does exist and it is quite efficient, as it prevents more serious forms of TB, but the protection it provides against pulmonary TB is variable. A newer vaccine was introduced in the US in 2004, and proved to be quite successful.